Oklahoma Joe's Longhorn Thermometer

I have an older Oklahoma Joe's Longhorn Smoker that needs a replacement thermometer. The bung in the smoker is 7/8 inch inside diameter thread. I can't seem to find a replacement thermometer that actually screws into the bung. Everything I see online is 1/2 inch with a retaining nut and washer to hold it in the larger size bung. Yet, I see new smokers in the local TSC Hardware with thermometers that will fit my smoker! Someone makes these, but I cannot find any. Does anyone have a source or suggestion on where I might find the proper thermometer that fits my smoker? Thanks!